osg多光源的實現

網上查找了關於osg光源的設置，基本上都是一個光源的，後來查找了一些資料，包括osg官方的例子。其實多個光源的實現非常簡單，只要多建立一個osg::Light的對象並設置對應參數即可。

以兩個光源爲例

osg::ref_ptr<osg::Group> createLight(osg::ref_ptr<osg::Node> node)
{
	osg::ref_ptr<osg::Group> lightRoot = new osg::Group();
	lightRoot->addChild(node);

	//開啓光照
	osg::ref_ptr<osg::StateSet> stateset = new osg::StateSet();
	stateset = lightRoot->getOrCreateStateSet();
	stateset->setMode(GL_LIGHTING , osg::StateAttribute::ON);
	stateset->setMode(GL_LIGHT0 , osg::StateAttribute::ON);//允許GL_LIGHT0光照
	stateset->setMode(GL_LIGHT1 , osg::StateAttribute::ON);
	


	//計算包圍盒
	/*osg::BoundingSphere bs;
	node->computeBound();
	bs = node->getBound();*/
	
	//創建兩個個Light對象
	osg::ref_ptr<osg::Light> light = new osg::Light();
	osg::ref_ptr<osg::Light> light1 = new osg::Light();

	//開啓光照
	light->setLightNum(0);
	light1->setLightNum(1);//0對應GL_LIGHT0，1對應GL_LIGHT1，默認情況下爲GL_LIGHT0
	//設置方向
	//light->setDirection(osg::Vec3(0.0f , 0.0f , -1.0f));
	//設置位置 最後一個參數1是點光源，0是平行光
	light->setPosition(osg::Vec4(0.f , 0.f , 800.f  , 1.0f));
	light1->setPosition(osg::Vec4(100.f, 100.f , 800.f  , 1.0f));

	
	//設置光源顏色
	light->setAmbient(osg::Vec4(0.3f, 0.3f, 0.5f, 1.0f));
	light1->setAmbient(osg::Vec4(0.3f, 0.3f, 0.5f, 1.0f));
	//設置散射光的顏色
	light->setDiffuse(osg::Vec4(0.75f, 0.75f, 0.75f, 1.0f));
	light1->setDiffuse(osg::Vec4(0.75f, 0.75f, 0.75f, 1.0f));
	//鏡面反射顏色
	light->setSpecular(osg::Vec4d( 0.8f, 0.8f, 0.8f, 1.0f ));
	light1->setSpecular(osg::Vec4d( 0.8f, 0.8f, 0.8f, 1.0f ));

	


	//設置恆衰減指數
	light->setConstantAttenuation(1.f);
	light1->setConstantAttenuation(1.f);
	//設置線性衰減指數
	light->setLinearAttenuation(0.f);
	light1->setLinearAttenuation(0.f);
	//light->setLinearAttenuation(0.f);
	//設置二次方衰減指數
	light->setQuadraticAttenuation(0.f);
	light1->setQuadraticAttenuation(0.f);
	//stateset->setAttribute(light,osg::StateAttribute::OFF);

	//light->setQuadraticAttenuation(0.f);

	//創建光源 
	osg::ref_ptr<osg::LightSource> lightSource = new osg::LightSource();
	osg::ref_ptr<osg::LightSource> lightSource1 = new osg::LightSource();
	lightSource->setLight(light.get());
	lightSource1->setLight(light1.get());
	lightRoot->addChild(lightSource.get());
	lightRoot->addChild(lightSource1.get());

	return lightRoot.get();

}